This
project is an integration of individual but interrelated tasks that
address environmental impacts in the South Florida ecosystem using
geochemical approaches. Externally derived nutrients, mercury and
sulfur are three of the most important contaminants currently affecting
this ecosystem. The scientific focus of this project is to examine
contaminant sources, the complex interactions of these contaminants
(synergistic and antagonistic), ecosystem responses to variations in
contaminant loading (time and space dimensions), and how imminent
ecosystem restoration steps may affect existing contaminant pools. The
Everglades restoration program is prescribing ecosystem-wide changes to
some of the physical, hydrological and chemical components of this
ecosystem. It remains uncertain, however, what overall effects will
occur as these components react to the perturbations (especially the
biological and chemical components) and toward what type of "new
ecosystem" the Everglades will evolve. The approaches used will be
extensions of previous field efforts by the lead investigators (Orem,
Krabbenhoft, Aiken, and collaborators), whereby we will enhance our
abilities to address land management and ecosystem restoration
questions. New methodologies implemented in this project will include
the use of environmental chambers (mesocosums), controlled laboratory
microcosm experiments, and isotopic tracers to provide a more
definitive means for addressing specific management questions, such as
"What reductions in toxicity (methylation and bioaccumulation) would be
realized if atmospheric mercury emissions were reduced by 75%?" or,
"Over what time scales could we expect to see improvements to the
ecosystem if nutrient and sulfur loading were reduced by implementation
of agricultural best management practices (BMP's) and the storm water
treatment (STA)
program?" Results of these biogeochemical investigations will provide
critical elements for building ecosystem models and screening-level
risk assessment for contaminants in the ecosystem, and this project
will be closely linked with projects addressing ecosystem modelling
(Reed Harris).

Project Objectives and Strategy:

The
major objectives of this project are to use an integrated
biogeochemical approach to examine: (1) anthropogenic-induced changes
in the water chemistry of the Everglades ecosystem, (2) biogeochemical
processes within the ecosystem affecting water chemistry, and (3) the
predicted impacts of restoration efforts on water chemistry. The
project uses a combination of field investigations, experimental
approaches (mesocosm experiments in the ecosystem, and controlled
laboratory experiments), and modeling to achieve these objectives.
Contaminants of concern will include nutrients, sulfur, mercury,
organic compounds, and other metals. Protocols for the collection of
samples and chemical analyses developed during earlier studies will be
employed in these efforts. Integration of the individual tasks within
the project is achieved by co-location of field sampling sites, and
cooperative planning and execution of laboratory and mesocosm
experiments. Results from all tasks within the project are archived
within a single database for use in Decision Management GIS systems and
ecosystem models. The needs of ecsosytem land and water managers to
understand the sources of contamination, the ecosystem response to
contamination, and the likely effects of restoration on water chemistry
are the principal driving forces behind the work plan proposed in this
study.

We
propose to carry out work in the following areas: (1) water quality
studies; (2) Field-scale and laboratory-scale experimental studies; and
(3) coordinating input of geochemical results into ecosystem models and
risk assessment studies being conducted by others. Our work tasks in
these areas will be framed within the context of the Everglades
restoration effort, and needs of ecosystem land and water managers to
understand how the restoration may affect water chemistry, biology, and
contaminant toxicity. The overall question we are addressing with this
effort is, "Near term changes to the Everglades are certain, but what
will be the ecosystem-level result of these changes and over what time
scales can we expect these changes to occur?" Our previous work has
answered many key questions regarding mercury, sulfur, and nutrient
cycling in the Everglades, and redefined several previously existing
paradigms about the general environmental chemistry of mercury. At the
same time, however, our work has revealed several critical information
gaps that we propose to address with this proposal.

This
project is designed to meet the needs of state and federal natural
resource managers who need information on environmental pollutants in
the Everglades, and what can be done to mitigate problems resulting
from these pollutants. Toxicity from sulfur and organic compounds are
two of the newer pollutants entering the ecosystem addressed by this
project. Many actions related to the Everglades Restoration project
could potentially affect the expression of mercury loading in terms of
its toxicity, including water levels, flushing rates, STA
implementation for sulfur and nutrient reductions and the use of
periphyton-based treatment cells, dissolved organic carbon releases,
etc. Our field and lab experiments are designed to address many of the
questions that surround how restoration plans may affect mercury
toxicity. Mercury emissions reduction is an enforcement decision facing
not only the State of Florida, but our Nation. Currently, we cannot say
with great confidence whether the mercury levels observed in the
Everglades are limited by the amount of mercury continually entering
the system, or some other substrate (e.g. sulfur). Although the
existing data from ACME
suggest that seasonal Hg loading from the atmosphere is concomitant
with higher observed methylmercury levels, there are many other
co-factors that could be causing this apparent correlation. Studies
proposed herein will address this critical management decision. This
project will also coordinate with efforts to perform a
multi-contaminant risk assessment by providing analytical and data
support as needed.

Potential Impacts and Major Products:

This
project addresses the major water chemistry issues currently affecting
the Everglades: (1) eutrophication from excess nutrients entering the
ecosystem, (2) sulfur contamination of the Everglades, sulfur toxicity,
and the relation of sulfur contamination to mercury methylation, (3)
mercury loading and bioaccumulation in the Everglades food web, and (4)
other contaminants of concern, including organic substances and metals.
Results have been used, and will continue to be used by ecosystem
managers in designing restoration efforts. Study results will provide
critical elements for building ecosystem models and screening-level
risk assessment for the principal contaminants impacting water quality
in the ecosystem (nutrients/sulfur/mercury/organics). Results.will
provide CERP (3005-1;3050-1,2,3,6,7,11;3060-1;3080 3,4,8,9,10), and GEER
management with quantitative information for critical decisions
regarding water quality and other competing issues (e.g. hydroperiod).
Experimental studies provide quantitative estimates of the maximum
sulfur, nutrient, and mercury loads producing permissable levels of
methylmercury in the ecosystem and impacting biota. Biogeochemical
recycling studies provide information that will assist in estimating
the time required for ecosystem recovery from chemical contamination.

Mesocosm
studies will provide quantitative estimates of the maximum sulfur,
nutrient, and mercury loads producing permissable levels of
methylmercury in the ecosystem. Biogeochemical recycling studies will
provide information that will assist in estimating the time required
for ecosystem recovery from chemical contamination. Results on water
quality studies from ASR
wells, Lake Okeechobee, and the Kissimmee River Basin will assist in
plans for Aquifer Storage and Recovery. Geochemical results will also
be incorporated into conceptual, mathematical, and risk assessment
models of the Everglades ecosystem. Nutrient and S
studies are focused on examining the sources of these contaminants, and
determining the rates of recycling and nutrient sinks in the ecosystem.
Results will assist managers in determining the fate of these
contaminants stored in sediments. The sediment studies will also
provide managers with information relevant to the effectiveness of
planned remediation methods. For example, will the STA's
be effective for long-term storage of nutrients removed from
agricultural runoff water? Also, what will be the effect of increased
hydrologic flow from the replumbing of the canal network in the
Everglades on nutrient and S loading to the ecosystem? All of the scientific efforts on Hg and S will be directly related to management questions surrounding how toxic MeHg production and bioaccumulation will be affected by the restoration efforts. Studies of S contamination relate directly to the issue of MeHg
production and bioaccumulation within the ecosystem, a threat to
wildlife and people in South Florida. We will continue active
participation in the South Florida Mercury Science Program, and provide
our findings to relevant management agencies in verbal and written
formats. We will solicit direct input from relevant management agencies
on the design of our mesocosm and laboratory experiments. We will
continue to be closely aligned with the Everglades Mercury Model
development to assure field and laboratory studies are in concert with
the model construction, coding, and the predictive questions being
asked of the model. We will coordinate our studies with risk assessment
studies related to mercury. Finally, we intend to integrate all the
information from this project into one consistent database, and be in a
Management Decision Support System that will be enabled with a GIS
driver (ARC View).

Major products from the study include USGS Open-File Reports, articles in peer-reviewed international scientific journals, USGS
Fact Sheets, abstracts and presentations at national and international
scientific meetings and at client agencies, contributions to USGS
and interagency synopsis reports, databases, and the electronic posting
of reports and databases on the Web (sofia.usgs.gov). Input of
geochemical data into ecosystem models and risk assessment studies will
also be a principal product of this project.

This
project integrates a number of individual but interrelated tasks that
use geochemical approaches to address contaminant and water quality
issues in the South Florida ecosystem. Task 1 of this project focuses
on biogeochemical processes, and the sources and cycling of nutrients,
S, and organics in the ecosystem. It coordinates with other tasks to
examine the complex involvement of nutrients, organics, and especially S in MeHg
production and bioaccumulation. A major focus is on ecosystem responses
to variations in contaminant loading (changes in external and internal
loading in time and space), and how imminent ecosystem restoration may
affect existing contaminant pools. Concentrations of contaminants are
determined in samples of surface water, porewater, groundwater, rain
water, sediments, soils, vegetation, and biota. Externally derived
nutrients, mercury and S are three of the
most important contaminants currently affecting this ecosystem. Rather
than a shotgun approach and massive sampling effort, sites for field
studies are carefully selected to answer specific management-relevent
questions and for field validation of results from mesocosm/microcosm
experiments and modeling studies. Major objectives of this task
include: (1) determining sources of contaminants to the ecosystem, (2)
providing quantitative descriptions of the biogeochemical processes
controlling the cycling of these contaminants of concern, (3)
describing the major sinks, speciation, and stabilities of contaminants
in the ecosystem, (4) developing geochemical budgets for contaminants
of concern on a regional scale, and (5) providing quantitative
information on contaminants for ecosystem models and risk assessment
studies conducted by others. The needs of ecosystem land and water
managers to understand the sources of contamination, the ecosystem
response to contamination, and the likely effects of restoration on
water chemistry are the principal driving forces behind the work plan
proposed in this study. Specific questions addressed by this task
include:

What are the major sources of contaminants to the Everglades?

How have anthropogenic-induced changes in water chemistry impacted the ecosystem?

How do biogeochemical processes within the ecosystem impact water quality?

What role does S play in the formation of MeHg?

How effective are STA's in removing contaminants of concern?

Will the Everglades STA's behave as low MeHg production sites?

What is the fate of contaminants in the Everglades?

How does fire/drought affect the recycling of contaminants and MeHg production?

What are the predicted impacts of restoration efforts on water quality in the ecosystem?

Integration
of Task 1 with other project tasks is achieved by co-location of field
sampling sites, and cooperative planning and execution of laboratory
and mesocosm experiments. Results from all tasks within the project are
archived within a single database for use in Decision Management GIS
systems and ecosystem models.

Study
results will provide critical elements for building ecosystem models
and screening-level risk assessment for the principal contaminants
impacting water quality in the ecosystem
(nutrients/sulfur/mercury/organics). Results will provide CERP (3005-1;3050-1,2,3,6,7,11;3060-1;3080-3,4,8,9,10), and GEER
management with quantitative information for critical decisions
regarding water quality and other competing issues (e.g. hydroperiod).
Results on water quality studies from Lake Okeechobee and the Kissimmee
River Basin will assist in plans for Aquifer Storage and Recovery.
Mesocosm studies will provide quantitative estimates of the maximum
sulfur, nutrient, and mercury loads producing permissible levels of
methylmercury in the ecosystem. Biogeochemical recycling studies will
provide information that will assist in estimating the time required
for ecosystem recovery from chemical contamination. Geochemical results
will also be incorporated into conceptual, mathematical, and risk
assessment models of the Everglades ecosystem.

Our previous studies showed that large portions of the northern Everglades are contaminated with S and nutrients (especially P). Isotope tracer studies demonstrated that both the S and P originate from canals draining the Everglades Agricultural Area (EAA), and is consistent with a source from agricultural runoff (P fertilizer, and S-containing fertilizers and soil amendments). S entering the ecosystem from contaminated canal water plays a key role in regulating the amount and distribution of toxic MeHg
production, a major contaminant issue in the Everglades. Other findings
from earlier studies include: (1) Taylor Slough is not a major source
of nutrients to eastern Florida Bay. (2) Phosphorus and nitrogen are
enriched in post-1980's sediments from Florida Bay, about the same time
as the first observations of seagrass dieoff. (3) Drought and fire play
a key role in remobilizing sequestered contaminants from sediments
(especially S), and stimulate MeHg
production in drought/fire-affected areas. Current research efforts
emphasize experimental studies to amplify and expand on earlier field
results. This includes the use of environmental chambers (mesocosms),
and laboratory studies (microcosms) to examine the effects of changing
environmental conditions (increased contaminant loading, changes in
hydroperiod, drought/fire) on contaminant concentrations and
methylmercury production. Our new research also includes contaminant
(nutrients, S, and organics) source, loading, sequestration, and
cycling studies in portions of the ecosystem not previously targeted,
including Lake Okeechobee and the Kissimmee River Basin, Big Cypress
National Preserve, and Shark River Slough and the southwest coast.

Work to be undertaken during the proposal year and a description of the methods and procedures:

(1) MeHg Mesocosm Experiments
- The major purpose of the mercury mesocosm studies is to examine the
effects (individual and synergistic) of mercury, sulfate and carbon
loading on MeHg production in the
Everglades. Previous work at field sites throughout the Everglades, and
mesocosm experiments conducted in 2001 and 2002 has shown that these
geochemical parameters are the key factors affecting MeHg
production and bioaccumulation in the Everglades. However, many details
of the effects of these parameters on the methylation of Hg in the
Everglades remain unknown, such as refinement of specific threshold
levels of each constituent. This information is directly applicable to
the effective management of the Everglades, and has important
implications for planners of the Everglades restoration program.

The proposed 2003 mesocosm experiments will be conducted at the 3A-15 site in the central Everglades, that provided the highest MeHg
response in the 2002 experiments, and also provides an ideal location
for the DOC and sulfate addition experiments, and for the sulfur
toxicity experiments described later. MeHg
mesocosm experiments will be conducted between mid June and the end of
October 2003. Conducting the experiment during this wet season/summer
period should produce the maximum MeHg
production signal, due to overall higher microbial activity in summer
months. Mesocosms used in the experiment will either be newly purchased
or previously used mesocosms that have never had mercury isotopes added
(such as controls, sulfate only, or DOC only additions). All previously
used mesocosms will be relocated at the 3A-15 site for this experiment.
Installation of the new mesocosms and relocation of existing mesocosms
(some moved from other sites in the Everglades) took place during
mid-April 2003 to allow time for reequilibration of the sediment and
water prior to initiating the experiment in June. After installation,
mesocosms are left open (six two-inch breather holes drilled on the
perimeter of each mesocosm) to its surroundings, which allows for free
exchange of water. At the start of experiments, the holes are plugged
with silicone stoppers to isolate the interior environment of the
mesocosm from the surroundings and maintain the presence inside the
mesocosm of the chemical.

Ten
mesocosms will be used for sulfate plus mercury additions. The ten
mesocosms will be grouped in sets of two for addition of sulfate at
five different dosing (i.e. concentration) levels and a single mercury
level of 1X ambient atmospheric (22 µg/m2; or 14.3 µgHg).
Experiments performed in 2000-2002 have adequately defined the
mercury-only addition response over a range of 0 to 2X ambient dosing
level. The sulfate dosing levels are 4, 8, 12, 16, and 20 mg/l,
based on the results of our 2002 mesocoms. The sulfate is added to the
mesocosms as sodium sulfate dissolved in site water. The appropriate
amount to be added to each mesocosm to reach the target concentration
is calculated based on the volume of water in each mesocosm. Each
dosing level has a duplicate mesocosm for quantifying natural
variability in the response, which is epically high for sediment-based
measurements (e.g., net methylation rates). A group of 6 mesocosms
(three sets of duplicates for each dosing level) will be used to
examine the effects of DOC and mercury isotope dosing at 3 different
dosing levels. DOC isolated from eutrophied sites near canal discharge
in Water Conservation Area 2A will be used for the experimental dosing.
Target addition levels for DOC will be about 30, 40 and 50 mg/l.
The DOC is added to the mesocosms as a concentrated solution and mixed
by gentle stirring of the surface water. Finally, a group of two
mesocosms will have DOC, sulfate, and mercury isotope added. These
mesocosms are intended to evaluate the synergistic effects of sulfate,
DOC, and mercury on MeHg production. The dosing level to be used in this mesocosm pair will likely be about 14.3 µgHg, 12 mg/l sulfate and 40 mg/lDOC. As with out previous mesocosm experiments, we will employ control
mesocosms to monitor the natural variability in the system and to
evaluate whether there are any unnatural "mesocosm" effects. To
establish natural variability and to control for mesocosm effects, two
mesocosms will be set aside as controls, and in addition two sites will
be established in the marsh near the control mesocosms as ambient
controls. The mesocosm controls will be plugged with silicone stoppers
and treated in a fashion similar to the experimental mesocosms, but no
dosing of any kind will be added.

The
experiment will commence on June 23, 2003. Samples of surface water,
porewater, Gambusia and sediments will be collected at the mesocosm and
outside controls to define the initial conditions of the site. After
sampling, all mesocosms will be plugged, and appropriate chemical doses
will be added. Follow-up sampling of the experimental mesocosms,
mesocosm controls, and outside controls for surface water, porewater,
Gambusia, and sediments will continue on days 1, 61, and 119 for .
After the initial doses, subsequent sulfate dosing is scheduled for
days 14, 28, 42, 63, 78, 91, and 105. Surface water is collected by a
peristaltic pump, and porewater (5 cm sediment depth) using a pump and
a micropiezometer. In-line filtering is used for all porewater and
surface water collections. Mercury-clean procedures are followed for
all sampling, which provides minimal contamination acceptable for all
analytes. Sediments are collected using a small push core to minimize
disturbance of the mesocosm interior. Analytes measured in surface and
porewater include: total mercury and MeHg
(ambient pools and isotope spikes), anions, cations, sulfur species
(sulfate, thiosulfate, sulfite, sulfide), nutrients (nitrate, ammonium,
and phosphate), DOC, iron and manganese, redox, dissolved oxygen, and
pH. Sediment geochemical analyses include: total mercury and
methylmercury (ambient pools and isotope spikes), total sulfur, sulfur
species (AVS, sulfate, disulfides, and organic sulfur), total and
organic carbon, total nitrogen, total phosphorus, and metals. Sediments
are also measured for various microbial parameters, including mercury
methylation rate, and sulfate reduction rates. Time-sensitive
parameters are measured in motel-room laboratories within hours of
sample collection. Samples for later analyses are stored in an
appropriate fashion (frozen, cool, etc.) and shipped back to laboratory
facilities at the various PI's labs (Middleton, WI; St. Leonard, MD; Reston, VA; Boulder, CO).
At the termination of the experiment (currently scheduled for October
14, 2003), the silicone stopper plugs are removed from the mesocosms,
and all equipment is removed from the site, with the exception of
mesocosms, which are left in place for potential future studies.

(2) Sulfur Toxicity Mesocosm Experiments
- Conventional wisdom holds that changes in macrophyte distributions in
the Everglades (cattail replacing sawgrass) have resulted from excess
phosphorus entering the ecosystem. However, areas of the ecosystem
where these changes have occurred are also heavily contaminated with S. Sulfur enters these areas as sulfate from canal discharge (the sulfate has been shown to originate in the EAA
from agricultural runoff and soil oxidation). The sulfate diffuses into
the anoxic sediments, and microbial sulfate reduction reduces the
sulfate to sulfide. Areas contaminated with high levels of sulfate also
have very high levels of sulfide in porewater. Dissolved sulfide is
highly reactive, and may also be toxic to both plants and animals. It
may reduce the ability of oxygen to penetrate to macrophyte roots, can
react with metals to make them unavailable for plant uptake, and can
impact biochemical processes of plant metabolism, such as nutrient
uptake. It is also worth noting that tree islands have largely
disappeared from regions of the Everglades impacted by sulfur
contamination. Our hypothesis is that high sulfide levels have played
an important, yet previously unrecognized role in the proliferation of
cattail in heavily S and P contaminated areas of the Everglades.

To test this hypothesis, we propose to employ mesocosms and sulfate dosing in sawgrass and cattail dominated sites of WCA 3A.
The sites will be in relatively close proximity to each other, probably
near tree islands where cattails are often found. Mesocosms would be
installed at these sites and allowed to equilibrate for a period of
couple months. As with the other mesocoms (described above), holes in
the sides of the mesocosms would allow exchange of water with the
outside during this equilibration period. The experiment would involve
addition of sulfate at three levels: 100 mg/l, 50 mg/l, and 20 mg/l;
each level run in triplicate. A pair of control mesocosms would also be
run at each site (no sulfate addition). A pair of external control
sites (no mesocosm, monitoring of external environment) would also be
employed at each location (cattail and sawgrass). Sulfate added to each
mesocosm would be calculated based on the volume of water at the time
of the experiment, and the amount needed to bring the mesocosms up to
the desired concentrations. Sulfate additions would initially be
conducted biweekly, and sulfate concentrations monitored to determine
future addition needs. Surface water in each mesocosm and in controls
(mesocosm and external controls) would be routinely collected (biweekly
to monthly) and analyzed for anions, cations, and nutrients. More
intensive sampling of surface water, and pore water, and biological
sampling would be conducted at least 4 times per year during the
initial period of the experiment. Surface and pore water will be
analyzed for sulfur species, anions, cations, and nutrients. Biological
studies to be conducted would include rates of respiration and
photosynthesis in macrophytes, abundance and types of periphyton on
submerged periphytometers, and numbers and types of macroinvertibrates.
We anticipate that the toxicological effects to plants may require many
months to be detectable, and therefore we are planning for this
experiment to run for two years. At the end of the study, intensive
surface water, pore water, sediment, and biological analyses will be
conducted. Coring and removal of plants from the mesocosms for further
study will be conducted at this time.

(3) Developing a predictive model for MeHg production in the Everglades and Stormwater Treatment Areas (STA's) -

STA's have been and continue to be constructed across the northern
Everglades, primarily for the removal of phosphorus from runoff waters
discharged to the Everglades. The full utilization of these STA's is an important aspect of the overall Everglades restoration plan, and achieving its goals. However, production of MeHg within certain STA's, particularly STA-2 Cell 1, have prevented full utilization of these wetlands for their
intended use and bring into question their net overall benefit.
Presently, flow-through operations of STA's must legally be stopped if MeHg in outflow waters exceeds that in inflow waters. This situation has occurred repeatedly in STA-2 Cell 1, both on start-up, and each subsequent year after drying and rewetting of the Cell. The SFWMD and the State of Florida seek information that would allow management of STA's to reduce or eliminate excess MeHg production events. Studies conducted by the ACME project over the past few years have shown the importance of sediment geochemistry to MeHg production, including the impacts of sulfate, sulfide and dissolved organic carbon on MeHg
production during wet conditions, and the importance of drying and
rewetting cycles on sulfur chemistry. Here we propose to build on that
information to generate information for the management of the STA's, and form a predictive capability to optimize locating and operating
these water treatment facilities to enhance the overall benefit to the
Everglades.

Our studies suggest that there are three main, manageable, controls on MeHg production in the STA's: antecedent soil chemistry, inflowing water chemistry, and interior water level maintenance. Since MeHg
production is substantially dependant on the amount and type of sulfur
present in soils, and on the mercury content of soils. Agricultural and
non-agricultural soils may have very different sulfur and mercury
levels because of land-use history, although to our knowledge little
information is available on soil sulfur and mercury chemistry in the STA's except for research sites in ENR and STA-2 Cell 1. Inflowing water contains three critical constituents that
strongly relate to methylmercury formation, transport and
bioaccumulation: sulfate, organic carbon and Hg. In addition, these
constiutents may change the character of soils in the long run. Last,
the timing and duration of flow-through of water of the STA's (i.e., hydroperiod) can dramatically affect MeHg production through the initiation of drying/rewetting cycles that have been shown to dramatically increase MeHg in Everglades soil.

Here we propose a set of studies conducted over two years that are designed to produce a predictive model for MeHg production in the STA's. The study will be carried out via agreements with USGS
researchers and with the Academy of Natural Sciences Environmental Research Center (ANSERC) in St. Leonard, Maryland. The objective of
this study is to develop a predictive capability based on soil
geochemistry, quality of inflowing water, and hydrologic conditions.
Although this research arises from the need to manage existing STA's, it will also be useful in site selection for any future treatment areas
and for planning and operation of future water reservoirs. We seek to
apply our knowledge of MeHg production gained in the Everglades to the STA's, through collection of comparative soil data for the STA's,
and by additional study of the influence of drying and wetting cycles
across a wider range of soil types. This new work will provide
information toward management of MeHg production in existing and planned STA's
of different soil types, through site selection, control of hydrology,
and water quality. The proposed study has several linked components:
(1) Survey of soil geochemistry, Hg and MeHg in STA soils; (2) Follow up examination of soil geochemistry, Hg and MeHg at ACME Everglades sites; (3) Examination of the influence of drying and wetting cycles across a wider range of soil types.

STA soil geochemistry - The Survey of soil geochemistry in STA's is an examination of STA soil geochemistry, especially sulfur, iron, and Hg/MeHg content. This component consists primarily of a field survey of soil geochemistry across the STA's. The objective of this survey is to test our Everglades-based understanding of MeHg production in the STA's. The primary drivers of MeHg
within Everglades surface soils are sulfur, Hg, organic carbon and
hydrologic conditions. A survey of soil conditions within the STA's will allow us to determine if the same drivers operate in STA soils, with their different land-use and hydrologic-maintenance histories. Currently operating STA's would be examined first in summer/fall 2003, then the survey would be expanded to STA's
under construction and planned for construction in spring 2004.
Site-selection criteria would include examination of a wide variety of
soil and land-use types, and the management needs of the agencies
responsible for Everglades restoration planning and operation. Specific
objectives of this component are to provide baseline data for
geochemistry and Hg/MeHg content of STA soils, and to evaluate the ACME conceptual model for control of MeHg production in Everglades soils for STA soils. Six sites within the STA's will be examined in fall 2003 and six more in 2004. Site access will be via helicopter. Mercury and MeHg
will be measured in surface soils, interstitial waters, surface waters,
periphyton and gambusia (should we do all these matrices?). Other
standard ACME
analytes to be measured include for bulk sediment: total sulfur, acid
volatile sulfide, chromium reducible sulfur, organic sulfur, organic
carbon, bulk density, and moisture content. Surface waters and pore
waters will be analyzed for sulfate, partially reduced sulfate species,
sulfide, total iron, total manganese, and dissolved organic carbon
using the previously referenced methods.

Soil biogeochemistry at ACME Everglades sites - The ACME
project examined eight discrete Everglades sites (ENR103, F1, U3, 2BS,
3A15, 3A33, TS7, and TS9) in detail, 2-3 times per year from 1995
through 1998, and that covered most of the north-to-south extent of the
ecosystem. These data have been used to generate a general conceptual
model for control of MeHg production in the Everglades. There are a number of reasons to look at the sites again in 2003. First, decreases in MeHg
in fish and wading birds have been observed in many areas of the
central Everglades during that time period, but there is no information
on any changes in MeHg in soils and water from the ACME
sites. Second, additional data density, especially during a different
hydrologic period, will provide a more robust data set for comparison
with STA soils, and
diagenetic modeling. Last, there are some additional parameters that
are needed for the diagenetic model that were not collected during
1995-1998, particularly solid-phase Fe speciation, which is needed to
model microbial Fe reduction. Periodic resampling of the ACME
sites is relatively inexpensive, and will provide valuable long-term
data on changes in Hg cycling in the Everglades ecosystem. Sampling
conducted at site ENR103 will provide valuable insights into STA biogeochemistry after several years of operation, particularly how long-term sulfate loading has impacted geochemistry and MeHg production in this soil. ENR soils were agricultural prior to conversion, and the high S content of these soils has minimized MeHg production at this site since start-up.

Specific objectives of this component are: (1) measure Hg/MeHg concentrations in soils, soil interstitial waters, surface waters and gambusia at the eight main ACME sties; (2) examine potential changes in MeHg concentrations at ACME sites, in comparison with declines in MeHg in wading bird and largemouth bass in the central Everglades; (3) examine changes in soil geochemistry and MeHg
in response to changing flow patterns and sulfate loading, particularly
in 2BS where substantially increased sulfate loading has occurred since
2000; and, (4) collect information on iron cycling that is needed for
construction of the diagenetic MeHg model.

Six to eight ACME
sites in the Everglades will be revisited in June or July of 2003.
Sites will include ENR103, F1, U3, 2BS, 3A33, 3A15, TS7 and TS9. Site
access will be via helicopter. Mercury and MeHg will be measured in surface soils, interstitial waters, surface waters, periphyton and gambusia. Other standard ACME
analytes to be measured include for bulk sediment: total sulfur, acid
volatile sulfide, chromium reducible sulfur, organic sulfur, organic
carbon, bulk density, and moisture content. Surface waters and pore
waters will be analyzed for sulfate, partially reduced sulfate species,
sulfide, total iron, total manganese, and dissolved organic carbon
using the previously referenced methods.

Examination
of the influence of drying and wetting cycles across a wider range of
soil type - This work will be an extension of successful studies of the
effects of drying and rewetting in STA-2 Cell 1, where substantial MeHg
production following rewetting was documented. We have hypothesized
that the pulse of methylation activity after rewetting of Everglades
and STA soils is
fueled by sulfate generated from the oxidation of reduced sulfur in
soils during the dry period. In order to follow up on this finding, we
conducted controlled drying and rewetting studies in the laboratory
with soils from STA-2
Cell 1 in spring 2002 and again in winter 2002/2003. Results from the
spring 2002 experiment support the hypothesis, whereby large increases
in sulfate concentrations in dried and rewet cores from both sites were
observed. Analysis of samples from the spring 2003 experiment is
underway.

During the spring 2002 experiment, MeHg
increased significantly in soils from both sites within 5 days of
rewetting dried cores, and stayed roughly the same over the next six
weeks. Water column MeHg concentrations lagged a bit behind soil, as MeHg in water derived from production in and flux from soils. The pulse of MeHg production following rewetting was rapid, but MeHg concentrations in surface soils remained high for at least six weeks following rewet.

MeHg concentrations in water over cores were maximal in 3A15 cores 3-4 weeks after rewetting, but continued to increase in STA-2 cores for at least 6 weeks.

This study confirmed that the high MeHg concentrations observed in STA-2 Cell 3 result from in situ production in surface soils immediately following rewetting. The soil chemistry at STA-2 Cell 3 is ideal for MeHg production, which is further fueled by the addition of high sulfate canal waters to the STA. In situ MeHg concentrations in the STA-2 soils were higher than the 4-year average for the ACME sites of highest MeHg production in the Everglades. The %MeHg at STA-2 cores after drying and rewetting substantially exceeded the the average %MeHg for the high MeHg sites in the WCAs. However, both soils examined in these experiments were relatively low S soils. Some of the largest responses in MeHg to drying and rewetting cycles in the Everglades have been in the high S northern Everglades. We believe that it is important to quantify experimentally the response of higher S soils to drying and rewetting in order to adequately model MeHg production within the STA's. We propose to use the same sample design used in spring 2003 to make these measurements, using high S soils from STA's
that have been constructed from agricultural lands. Two additional soil
types would be examined. This work would be undertaken in winter
2004/2005, using FLFY 2005 funds. Sites will be chosen after completion of the STA soil survey and in consultation with SFWMD.

Specific objectives of this component are: (1) examine the magnitude and timing of MeHg production in response to drying and rewetting cycles across a wider range of STA soil types, particularly high S-content soils; and (2) compare the response of high and low S soils to drying and rewetting, and apply this understanding to management questions for the STA's. These data will be used by others in the development of a diagenetic MeHg production model.

Experimental studies of the influence of soil drying and rewetting on MeHg
production will be done using the same design and facilities used in
for spring 2003 experiments. Cores will be collected in Florida and
driven to ANSERC, where they will be dried in a temperature and
light-controlled environment. The amount of drying time will be
determined after final analysis of the spring 2003 experiments, in
which cores were dried for months before rewetting, in order to provide
a comparison with cores that had been dried for a few weeks (spring
2002 experiments).

Replicate
soils cores (~40) will be collected intact from each of chosen sites.
In addition to cores collected for laboratory experiments, additional
samples will be taken to assess mercury and sulfur biogeochemistry in
situ at the time of collection. Cores will be collected in 7 cmPVC
barrels and in 10 cm Teflon barrels. Teflon barrels will be used for
cores from which water samples will be taken. Cores will be returned to
the Academy of Natural Sciences Environmental Research Center (ANSERC)
and held at ambient summer temperature with sunlight spectrum lighting.
Some cores will be maintained wet as controls, while most cores will be
allowed to dry. After drying, cores will be rewetted with water from
the appropriate inflow canal, dosed with a stable mercury isotope. The
soil, surface water, and pore water from the rewetted cores and the
controls will be sampled at approximately 0, 7 and 49 days after
rewetting. The time course was chosen based on results in experiments
to date. Solid phase samples and pore water samples will be taken by
sacrificing whole cores; overlying water will be sampled repeatedly
from cores in Teflon barrels. Water over cores will be replaced with
canal water as need to maintain volume. The soil will be analyzed for
total and methyl-mercury using ICP-quadrupole mass spectrometry.
Digestion or distillation of samples for total and methylmercury
analysis will be as previously described by ACME.
Other soil measurements will include total sulfur, acid volatile
sulfide, chromium reducible sulfur, organic sulfur, organic carbon,
bulk density, and moisture content using standard wet and instrumental
analytical methods. The surface water and pore water will be analyzed
for filtered total mercury, methylmercury, sulfate, partially reduced
sulfate species, sulfide, total iron, total manganese, and dissolved
organic carbon using the previously referenced methods. Temperature and
dissolved oxygen will be monitored in water overlying cores.

(4) Field Studies

A
number of different field studies are being conducted to examine
concentrations, sources, sinks, and biogeochemical cycling of various
contaminants in the ecosystem. Task 1 focuses on nutrients, sulfur, and
organics.

Big Cypress National Preserve (BCNP) - A preliminary surveys in BCNP in FY03 was conducted to examine concentrations and sources of nutrients and sulfur. Results showed levels of nutrients, sulfur, and MeHg to be generally low, except in the area around the L-27 feeder canal. This canal had relatively high S and P levels. Plans to divert water from this canal into BCNP could, therefore have significant consequences with respect to eutrophication and MeHg production in this currently pristine area. We propose to follow up on this preliminary work in FY04 with more detailed studies, especially in the region of the L27 feeder
canal. We will collect surface water, groundwater, porewater, and
sediment samples from selected sites in BCNP,
and analyze them for nutrients, sulfur species, sulfur isotopic
composition, uranium, and uranium activity ratio. Uranium and uranium
activity ratio is used as a tracer for phosphorus sources (agriculture,
groundwater, background). Similarly, sulfur isotopes will be used to
trace the sources of sulfur entering Big Cypress.

Canals - Canals draining the EAA
and entering the Everglades are the principal conduit for many of the
important contaminants entering the ecosystem. Although the SFWMD monitors the canal system for P and other constituents, monitoring of the canal system for S is lacking. Since 1998 we have been conducting routine monitoring of the canal systems for S concentrations and isotopic composition. This will provide background data for models of S entering the ecosystem. We propose to continue this work in FY04.

Florida Bay - The ACME
II group (Krabbenhoft/Orem/Aiken) will examine the biogeochemistry of
mercury methylation in Florida Bay sediments using a multifaceted field
approach. Task 1 will examine sulfur speciation and concentrations in
sediments and sediment porewater. We will use an analytical scheme for
sulfur speciation and quantification of sulfur species that we used
previously in the Everglades and Florida Bay. The range of
concentrations and biogeochemical processes involved in MeHg
production in the bay may be quite different from those in the
freshwater Everglades. This study will provide baseline data for
developing a conceptual model of the mechanism og MeHg production in Florida bay sediments.

Transect studies in Everglades National Park (ENP) and Loxahatchee National Wildlife Refuge (LOX) - These studies will examine changes in water quality along selected transects in both ENP and LOX. The ENP
studies will focus on transects near the area where water from the L67
canal is discharged into the Park. Preliminary studies conducted by the
South Florida Water Management District has identified another MeHg "hot spot" near this zone of discharge. Previous USGS
work has shown that the L67 canal has significant sulfate levels,
possibly originating from the Miami Canal. This sulfate could be
stimulating sulfate reduction and MeHg
production at the L67 discharge site. This work, conducted jointly with
Task 2 of this project will examine the distribution of MeHg production, and sulfur geochemistry in the targeted area, and determine the causes of the MeHg "hot spot". We will also explore ways to mitigate MeHg production in the target area of ENP.

The studies in LOX will focus on transect work from the edges of LOX near newly established STA's, to the center of the refuge. Preliminary studies suggest that leakage of contaminated water across the levees bounding LOX
is occurring. Contaminants entering the refuge include major cations,
sulfur, Hg, anions, and nutrients. These contaminants may have
significant impacts on water quality within LOX,
with largely unknown impacts on biotic assemblages within the refuge.
This study will provide basic information on changes in water quality
parameters in the refuge. Work is planned to be coordinated with Paul
McCormick, USGS, BRD.

Planned Outreach:

Results
from this Task will be communicated to interested parties using a
number of different mediums. We will continue to publish papers in the
peer-reviewed scientific literature, and to make presentations at local
and international scientific meetings. Databases (sulfur database,
Florida Bay database, nutrients database) will be posted on the Sofia website. This approach supplies technical information, new scientific
ideas and hypotheses, conceptual models, and data to other scientists
and technical/scientific resource managers. These scientific
publications and presentations (see Products List) present data and
ideas useful to the restoration effort in South Florida, but also
useful in a more general scientific context, and applicable to
contamination problems and restoration efforts beyond South Florida.

Technology
transfer is also a major part of our research effort. We provide
training and advice on analytical methods, equipment, and sampling
techniques to many of the state and federal agencies operating in South
Florida. This often includes having individuals from cooperating
agencies accompany us on field sampling trips. A recent example of this
is a demonstration to the South Florida Water Management District on
pore water collection and redox measurements in the Everglades.

We
also recognize the need to communicate ideas and results to a
non-technical audience that includes non-technical/scientific resource
managers, government officials, legislators (state and national), local
residents, and the general public. To address this need we will use a
number of approaches. We will continue to produce Fact Sheets aimed at
a general audience. We have a Fact Sheet planned for FY 2003 entitled "Sulfur Contamination in the Everglades", which will
explain this issue in lay terms. We make presentations, as requested,
at public forums on issues related to the Everglades, as well as to
federal and state officials concerned with Everglades Restoration. We
have also given interviews and provided tours of field sampling trips
to representatives of regional and national publications (newspapers
such as the Miami Hearld, and magazines such as Audubon). Several
newspaper and magazine articles have resulted.

As
researchers for a non-regulatory federal agency, we recognize the need
for even-handedness, and full disclosure of scientific results
(following appropriate internal review) to all interested parties.
Results of our research are posted on web sites available to all
interested parties, and presentations are made at meetings open to all.
We have also had lengthy phone and personal discussions with
representatives (technical and legal) of parties on all sides of
controversial issues surrounding the Everglades restoration.

C. BRIEF DESCRIPTION ON HOW PROJECT TASKS SUPPORT THE DOI AND USGS EVERGLADES RESTORATION SCIENCE PLANS

This
project primarily addresses water quality goals for Everglades
Restoration. This is primarily addressed in Goal 1B, Get the Water
Quality Right of the USGS
Science Plan for Everglades Restoration. Nutrients, sulfur, and mercury
represent the major contaminants impacting water quality within the
ecosystem. This project addresses sources, cycling impact, and fate of
these contaminants in the Everglades. Aspects of the project addressing
individual portions of the USGS Science Plan are shown in italics below:

What are the water-quality characteristics of a "healthy" Everglades? Project provides data on the background sulfur, nutrient, and mercury concentrations and loads in the Everglades.

How does water quality relate to the major biogeochemical processes, and current land use and management activities? Project provides information on sulfur and nutrient biogeochemical cycling in sediments, and biogeochemical production of MeHg in the range of different environments in the ecsosytem, and in STA's and other planned restoration activities.

How do we restore and protect water quality in the ecosystem? Project provides data used to recommend strategies to reduce sulfur and nutrient contamination, and MeHg production in the Everglades.

What
contaminants are currently present, and what contaminants (and their
distribution) might we expect to see after restoration? This project provided the first information of sulfur contamination in the Everglades and its link to MeHg production in the ecosystem. It will provide new information on the impact of restoration on sulfur and MeHg contamination in the Everglades.

What are the ecosystem risks associated with current water quality? The
project will provide basic information on the effects of sulfur
toxicity on macrophytes and periphyton in the ecosystem (a first), and
the impacts of MeHg bioaccumulation on fish and higher trophic level organisms.

How do freshwater inflows affect water quality in the coastal ecosystem? The project is just starting work on MeHg production in the coastal zone, and what biogeochemical processes control MeHg production in that environment.

How do contaminants affect plant and wildlife species? Project addresses MeHg bioaccumulation in biota, and the effects of sulfur toxicity on macrophytes and periphyton.

Will recovered ASR waters be compatible with receiving environments and aquatic and terrestrial biota? Sulfur in ASR waters will be a major contaminant issue of concern.

SO2. Determine the historical ecological setting of the Everglades.

What were the water-quality characteristics of the pre-drainage ecosystem? Project addresses historical sulfur and nutrient conditions in the Everglades and coastal areas.

What are current water quality conditions across the South Florida environment? Project field studies address water quality with respect to nutrients, sulfur, mercury, and organics.

What are current contaminant burdens in plants and wildlife in the Everglades? Project addresses MeHg in fish.

How do we determine reasonable water quality restoration targets and rank their potential for success and sustainability? Only viable project in South Florida addressing this question for sulfur and mercury in the ecosystem.

How
can we protect those areas with good water quality currently, and can
we restore or improve conditions where significant impacts have been
observed? Field and experimental studies in the Everglades and the STA's will address this question for sulfur and mercury.

What
contaminants are currently present, and what contaminants (and their
distribution) might we expect to see after restoration? Field and experimental studies in the Everglades and the STA's will address this question for sulfur and mercury.

SO4. Monitor ecosystem response to change.

What are the relative impacts of the various restoration activities on water quality at the ecosystem scale? Effects of restoration on water quality with respect to sulfur and mercury are being studies by this project.

Do
we have the adequate monitoring systems in place to detect changes to
water quality in response to restoration activities; and, if not, what
systems are necessary? Project monitors the ecosystem in canals, marshes, tree islands, rivers and streams, etc. for sulfur and mercury.

SO5. Predict ecosystem response to anthropogenic and natural changes.

Do we have the necessary tools presently to predict water quality changes? And, if not, what tools are needed? Project results are used in models to predict water quality changes in sulfur and mercury as restoration proceeds.

What are the predicted impacts and benefits to water quality from restoration efforts:

Impacts or benefits of changes in water supply? Project addresses effects of increased sulfur loads from increased water flow to ENP.

Impacts of specific structures? Specific canals and water control structures addressed for sulfur and mercury loads.

Impacts of altered flows on estuary and marine ecosystems? Project addressing effects on mercury and MeHg frlo from freshwater to coastal areas.

The project also addresses the following DOI Objectives for Everglades Restoration:

Research to determine long-term effects of low-level contamination. Project addresses contamination from both sulfur and mercury at low levels.

C. Decompartmentalization of Water Conservation Area 3

What Is Needed

Water quality studies - Studies of water quality in WCA 3 (sulfur, Hg, nutrients) has been and will continue to be a major objective of this project. Decompartmentilization of WCA 3 will likely result in increased sulfur loads to the ecosystem and dramatic effects in increasing MeHg production in parts of WCA 3 and ENP.

D. Additional Water for the Everglades National Park and Biscayne Bay Reconnaissance Study

E. Risks to Fish and Wildlife from Contaminants in Stormwater Treatment Areas (STA's)

What Is Needed

Monitoring of actual uptake of contaminants into the food chain. Bioaccumulation of MeHg addressed by this project

H. Arthur R. Marshall Loxahatchee NWR Internal Canal Structures

What Is Needed

Data to support an integrated hydrodynamic and water quality model - Project will provide information on contaminants entering the refuge from STA's and canals, and on MeHg production resulting from contaminant influx.

B. Water Quality Including Contaminants

B. 1. Water Contaminants related to CERP Projects

What Is Needed

Methods
need be developed to determine what trust resources are at greatest
risk given potential contaminant exposure scenarios. Risk management
decisions are often based on what ecological component is at risk from
a particular action reflecting that certain components have greater
management value than others. Project data will assist in determining what components are at greatest risk.

Potential
exposure scenarios for trust resources need to be adequately
characterized in order to more accurately understand their risk from
exposure to sediment and soil contaminants. Sulfur toxicity, phosphorus
recycling, and MeHg production from sediments are major project study areas.

In
addition to improving food chain models, a protocol needs to be
developed for assessing bioaccumulation in trust resources. A decision
process needs to be developed that will determine if the risk of a
bioaccumulation needs to be assessed. Bioaccumulation of MeHg at the base of the food chain is a major objective of this project.

Information
on contaminant interaction and toxicity (synergism) must be developed
to assess risk to wildlife simultaneously exposed to multiple
contaminants. Most risk assessments determine risk to wildlife from
exposure to single contaminants, not from multiple contaminants as
there is uncertainty in the synergistic interaction effects on
toxicity. Studies of the interactions of Hg, sulfur and nutrients (synergistic and antagonistic) are major study areas of this project.

Risk
assessments for fish and wildlife due to exposure to methyl mercury
would benefit from an investigation into the relationship of factors
affecting methyl mercury formation. Obviously a major goal of this project with a focus on sulfur and mercury.